Tubular components such as pneumatic tire body plies, have previously generally been built by utilizing woven fabric and calendering the same with rubber stock which, when cut to size, is wrapped about a tire building drum with overlapping ends to produce a tire carcass. The formation of the overlapping seam is generally disadvantageous in that, the discontinuity caused by the seam produces not only a lapped splice, but also an asymmetrical construction tending to cause a force unbalance in the completed tire and a sidewall undulation.
In order to avoid this lapped or seamed construction, extrusion has been employed in the prior art for producing a generally tubular elastomeric ply made up of concentric tubular streams of elastomeric material which provides a tubular extrudate, which when severed into predetermined axial lengths, provide a seamless body ply element. An example of such a coextrusion to form such a seamless body ply is shown in U.S. Pat. Nos. 4,657,718 and 4,578,024.
It is desirable for efficient and timely utilization of the produced seamless body ply that the ply be transferred to a new production station while retaining its geometry, that is, its cylindrical or tubular configuration without undesirable distortion or wrinkling since the extrudate will be in a relatively soft and heated state. To accomplish this, a system is required which can rapidly and accurately collect, envelop and separate the continuous tubular extrudate into predetermined axial length sleeves while moving the extrudate and the severed sleeve along a production axis enabling the extrudate to be positioned for subsequent cuts as the previously severed sleeve is moved to a discharge station for use in the tire manufacturing procedure. It is critical during the movement and cutting of the tubular extrudate to maintain a constant control of the configuration of the soft extrudate while providing a continuous movement thereof so as not to affect the overall continuous tire manufacturing procedure.
It is also necessary in providing such a satisfactory system, method and apparatus that gripper mechanisms be provided for effectively maintaining the shape of the extrudate and that a cutter mechanism be employed which provides a clean, smooth cut through the extrudate without tearing or deforming the cut edges thereof.
Various prior art devices have been used for gripping and moving heavy rigid tubular material and for cutting the same, and other prior art systems have been developed for performing operations on tubular materials. With respect to the overall handling and cut-off system, the following ten patents are believed to be examples of the closest known prior art.
U.S. Pat. No. 3,267,783 discloses a method and apparatus for handling and cutting extruded lead tubing which is used as sleeves for splicing cables. The apparatus includes a cutting mechanism, a two portion gripping mechanism, a transfer mechanism and a receiving mechanism, all of which are associative with an extrusion press. In operation, a continuous length of tubing is extruded from the top of a press and is clamped between the jaws of a clamping mechanism. The tubing travels through the jaws until a desired length of sleeve is severed. During cutting, a portion of the tubing held by the jaws is under tension with respect to the portion of the tubing below the cutting saw in order to prevent binding.
U.S. Pat. No. 4,339,868 discloses a system for automatically manufacturing plastic tubular elements having a feeder which feeds nylon tubes to a conveyor in combination with a cutter to cut predetermined lengths of tubing. Clamping jaws grasp the tube and move it to a spaced position where the tube ends are grasped by another pair of jaws.
U.S. Pat. No. 3,559,520 discloses a cutting saw machine with a clamping device wherein a saw can be moved longitudinally in a synchronized fashion. The jaws grip the leading end of the stock and the portion to be cut is held in a secure fashion to insure a clean cut therebetween by a rotatable saw which is movably mounted on a carriage.
U.S. Pat. 3,808,928 discloses a device for forming a tube and cutting the same in which the tube is gripped between jaws and is cut by a saw travelling on a guide.
U.S. Pat. No. 3,801,398 discloses a method for manufacturing tire inner tubes having air valves. The apparatus includes an extruder which delivers five parallel tubes to an upper portion of a conveyor. A cutting knife cuts five tubing portions from the extruded tubing. Each tubing portion is provided with an air valve and the cut portions are transferred to a delivery conveyor where the ends of each tubing portion are joined.
U.S. Pat. No. 3,982,980 discloses a method of extruding a resin tube by cutting off lengths of the tube to form a plurality of cartridge barrels. Barrel cylinders are formed by extruding a continuous length of relatively thin-walled resin tubing with constant inside and outside diameters. The extruded tubing is cut off in several generally known ways, i.e. by cutting apparatus which will move with the tubing and cut the tubing on the fly, or a cutting device which can momentarily stop the tubing after the cut is made.
U.S. Pat. No. 4,283,241 discloses an apparatus for forming radial ply tire carcass plies from a continuously produced tube from which axial sections are cut by cutting means. Folding rolls fold the projecting ends of the tube sections to form bead cores. A transfer device includes two radially movable gripper arms which extend into and engage the open ends of the tubular extrudate.
U.S. Pat. No. 4,492,136 discloses a cutting system for forming pipe casing in an apparatus which is designed to cut a generally circular cross-sectional pipe. The apparatus has two opposed cutters which are separated from each other by 180.degree. and move from a central neutral position over approximately 90.degree. in each direction so that upon rotation of the cutter they can complete a 360.degree. circle about the pipe. The apparatus further includes a cutter assembly mounted on an annular trackway. After the pipe casing to be cut is positioned within a cutting area, cylinders are actuated to push and clamp the pipe against curved backwall stops of a fixed centering member. The cutter assembly is then moved into position which includes two opposed driven rotatable cutting blades which cut the pipe into predetermined lengths.
U.S. Pat. No. 3,044,336 discloses a method of cutting axially movable round bars. The apparatus includes a reciprocating carriage mounted on sidewalls of a bench frame. The carriage is provided with guide rails on which an auxiliary carriage is mounted for limited oscillating movement. A cutting device is carried on the auxiliary carriage and when a predetermined length of tubular member has passed through a supporting bench, the work is rigidly connected to the auxiliary carriage wherein the work will be under tension. After the tubular member is cut, the cutting tool returns to its inoperative position so that the work clamping mechanism will be relaxed and the carriages can be returned by a chain drive to their initial position.
U.S Pat. No. 4,484,966 discloses a method of manufacturing carcass bands reinforced by cords to form a radial tire. An axially movable mechanism is provided on a retaining pipe, downstream of which is located a severing machine which severs the hose at predetermined lengths by using either laser beams or rotary cutters. A pair of clamping members also are provided which are driven by reciprocating members for clamping the pipe. A second retaining mechanism which retains the severed hose, is moved axially forward of the retaining pipe, which is now secured by other clamp members, with the severed hose being transferred to a predetermined location. However, the extruded sleeve is not maintained in tension as it moves along its work path as is the extrudate of the present invention, but is permitted to become slack and distorted.
However, none of the devices set forth in the above patents disclose the specific arrangement of a cutter and two opposed clamps as in the invention described below, in which both the cutter mechanism and the clamping mechanism are designed to encircle the tubular material to be cut, or that the cutter mechanism extends axially within the tubular material and then rotated for severing the same.
The following five prior art patents relate to cutting devices of the general type as set forth in the present invention:
U.S. Pat. No. 4,492,136 also discussed above, discloses two or more cutter sections which can comprise less than 360.degree. individually, but together can be rotated over 360.degree. to effect a complete cut about a tubular element.
U.S. Pat. No. 3,249,998 discloses a pipe cutter having a plurality of disc cutters. The cutter includes a clamping member having a pair of adjacent parallel diverging arms. A pivotal connection between one end of the arm and a spacer permits the clamping member to be pivoted into its correct position. Aligned openings in the arms provide clearance to receive a shaft on which a cutter wheel or discs are rotatably supported. The cutter discs act to cut the walls of the pipe in response to rotation of the cutter unit.
U.S. Pat. No. 3,456,856 discloses a pipe cutting tool which includes four arcuate segments mounted on an inner ring and four additional segments mounted on an outer ring. A plurality of cutters are forced into a pipe to produce a series of uniform indentations about the pipe. Both of the rings are separately hinged so they can encircle a pipe before cutting. A cylinder rotates the outer ring structure relative to the inner ring structure to pivot the cutters and produce a smooth fracture in a cutting operation.
U.S. Pat. No. 4,175,455 discloses a cutting device for cutting a block of continuously extruded urethane foam. The apparatus includes an infeed conveyor and a stationary cutting platen positioned at the end of the conveyor. As the foam moves on the conveyor in a longitudinal direction, it is cut over the platen into a plurality of sections which are taken away by an outfeed conveyor. A cutter saw assembly moves longitudinally and vertically to completely cut the foam when over the platen. The saw first moves longitudinally at the same speed as the conveyor and then moves downwardly while still moving longitudinally to effect a cut.
Russian Patent No. 148,743 discloses an "on the fly" type cutter for cutting pipes after they are extruded. The apparatus includes a plurality of cutting blades arranged to encircle the pipe, with one end of each blade being pivotally mounted on a ring capable of rotating about a horizontal axis. The other end of the blades are attached to sliding elements which are arranged for sliding in radial guides in a sleeve rigidly mounted to the cutting apparatus.
None of these five patents disclose the precise structure of the external cutter of the present invention; insofar as none of them include two pivotable cutting heads which are movable in addition to a stationary central cutting head. Furthermore, none of these patents show a cutter which extends axially and rotationally within the tubular extrudate for severing the same.
The following two patents are pertinent with respect to the particular gripping apparatus and mechanism of the present invention:
U.S. Pat. No. 4,484,966, also discussed above, utilizes two retaining mechanisms, each having a plurality of suction grippers in the form of vacuum cups. This mechanism has vacuum cups mounted on the inner end of radially movable piston rods. The outer portion of a cylindrical hose which is to be cut is attracted and retained initially by these vacuum cups.
U.S. Pat. No. 3,249,998, also discussed above, discloses a clamping member comprising pivotally connected adjacent arms which open to surround a cylindrical pipe prior to a cutting operation.
However, neither of these patents discloses a three part pivotal clamping mechanism having a stationary central member and two pivoting members which are designed to encircle an entire flexible tubular element.